i) Field of the Invention
The present invention relates to an obstacle avoidance apparatus for automatically piloting or controlling an aircraft or an automobile so as to avoid an obstacle to go toward a destination and a radar information processing apparatus for predicting a route to the destination.
ii) Description of the Related Arts:
Conventionally, in an obstacle avoidance apparatus for such a purpose, from information of a target, an obstacle and a destination in two dimensions, characteristic amounts required for grasping a positional relationships between these are extracted, and a piloting or controlling amount to the target is determined based on the postional relationshipS.
FIG. 12 illustrates a conventional obstacle avoidance apparatus in two dimensions, constructed in accordance with the prior art as shown in "Dynamic Obstacle Avoidance Control of Movable Robot by Using Fuzzy Inference", by Yohichiro MAEDA and Seiichi TAKEGAKI, proceedings of Robot Society of Japan, Vol. 6, No. 6, 1988. In this case, from positional relationship between a target to be controlled, an obstacle and a destination, a control amount to the target is output.
First, the construction of the conventional obstacle avoidance apparatus will be described in connection with FIG. 12. In FIG. 12, a target data generator 1 observes a target to be navigated and outputs observation values of the target, and a movable obstacle data generator 2 outputs obstacle data. A characteristic amount extractor 4 outputs characteristic amounts for grasping a relationship between the target and the obstacle and between the target and the destination, and a control amount determiner 5 outputs a control amount for controlling the target. In the target data generator 1, a sensor 11 observes the target and outputs corresponding signals, and a data processor 12 receives the corresponding signals output from the sensor 11 and processes the same to output a position Pr and a speed Vr of the target. In the movable obstacle data generator 2, similar to the target data generator 1, a sensor 13 observes a movable obstacle and outputs corresponding signals, and a data processor 14 receives the signals output from the sensor 13 and processes the same to output a position Po and a speed Vo of the obstacle. In the characteristic amount extractor 4, a static risk calculation element 26 calculates and outputs a static risk .alpha. caused by the static relationship between the target and the obstacle from the position Pr and the speed Vr of the target output from the target data generator 1 and the position Po and the speed Vo of the obstacle output from the movable obstacle data generator 2, and a dynamic risk calculation element 27 calculates and outputs a dynamic risk .beta. caused by a relative speed of the target to the obstacle. Further, a movable obstacle avoidance amount calculation element 16 receives the static risk .alpha. and the dynamic risk .beta. output from the static risk calculation element 26 and the dynamic risk calculation element 27 and outputs an avoidance control amount C required for avoiding the obstacle based on the static risk .alpha. and the dynamic risk .beta., and a destination control amount calculation element 23 calculates and outputs a destination direction vector as a destination control amount D required for heading the target toward the destination based on the target observation values Pr and Vr output from the target data generator 1 and destination data stored in a destination data memory 21. In the control amount determiner 5, a control amount determination element 28 determines a balance between the avoidance control amount C output from the movable obstacle avoidance amount calculation element 16 and the destination control amount D output from the destination control amount calculation element 23 according to a rule table 29 and outputs a control amount M of the target.
The operation of the conventional obstacle avoidance apparatus described above will now be described in connection with FIG. 13. First, in step ST1, the observation of the target is carried out by the sensor 11 and the signals of the sensor 11 are processed by the data processor 12 to output the target observation values Pr and Vr in the target data generator 1. In step ST2, similarly, the observation of the obstacle is carried out by the sensor 13 and the signals of the sensor 13 are processed by the data processor 14 to extract the obstacle observation data Po and Vo in the movable obstacle data generator 2. Next, moving forward to step ST4, in order to obtain the avoidance control amount C and the destination control amount D as the characteristic amounts, the processings in steps ST4a to ST4d are executed in the characteristic amount extractor 4. That is, in step ST4a, the static risk .alpha. is calculated in the static risk calculation element 26 and in step ST4b, the dynamic risk .beta. is calculated in the dynamic risk calculation element 27. Also, in step ST4c, the control amount D in the destination direction is calculated in the destination control amount calculation clement 23 and in step ST4d, the movable obstacle avoidance amount C is calculated in the movable obstacle avoidance amount calculation element 16. In step ST5b, from the characteristic amounts, the control amount M controlling the observed target is determined in the control amount determiner 5. In step ST8b, it is discriminated whether or not it is possible for the target to reach the destination. When the answer is YES, the operation is finished, or when the answer is N0, the operation is returned to step ST1 to repeat the above-described operation again.
In the conventional obstacle avoidance apparatus, as described above, the characteristic amounts are extracted by the above arrangement and the control amount of the target is successively determined until the target reaches the destination while avoiding the obstacle. However, considering a three-dimensional obstacle, the obstacle is not a point but a landform or terrain having a complicated form and a height and thus a steering the obstacle avoid can not be achieved in the relatively simple manner just described.